You receive the error message if one of the following conditions is true:
- You are trying to use the same product key on multiple computers, and you exceed the limit that is specified in the Microsoft Software License Terms. The Microsoft Software License Terms are located in the product installation folder on your computer. For some products, the Terms allow activation on more than one computer. See the Microsoft Software License Terms for more information, including how many computers that the product can be activated on.
- You made significant changes to your computer's hardware, such as installing a new RAM card, a video card, or other hardware.
- You reformatted the hard disk.
If you are not exceeding the number of activations that is allowed by the Microsoft Software License Terms, click the Activate By Phone button, select the location, and then call the telephone number that is displayed. For example, for the United States, the number is (866) 825-4797. For the United Kingdom, it is (44) (203) 147-4930.